Genetic Resources In Use: The Case of Tetraploid Wheat.the Global Durum Genomic Resource (GDGR), theTetraploid Core Collection (TCC) and the Tetraploid WheatPangenome

Cultivated tetraploid wheat—including durum or pasta wheat—originated from wild emmer (Triticum dicoccoides (Asch. & Graebn.) Schweinf.) and evolved through two consecutive, partly independent rounds of domestication and spread from the Fertile Crescent along eastern–western and northern–southern trajectories. These migrations led to the differentiation of a range of Tetraploid genetic resources adapted to contrasting environments and multiple abiotic and biotic stresses. As donors of the BB and A A genomes for both durum and bread wheat, these resources represent a huge reservoir of genetic diversity for modern breeding—critical for addressing challenges posed by global climate change. Here, we present results from an international collaborative effort aimed at generating, characterizing, and mobilizing genomic resources of tetraploid wheat (Global Durum Genomic Resources, GDGR). The GDGR comprises 3,142 non-redundant single-seed descent (SSD) purified tetraploid accessions genotyped with the iSelect 90K SNP array. From the phylogenetic and haplotype-based population structure analysis, a Tetraploid Core Collection (TCC) of 450 core accessions was established, representing the diversity in wild and domesticated emmer, T. turgidum subspecies, durum wheat landraces, and modern varieties. This collection underpinned the development of a Tetraploid Wheat Pangenome, sequenced using long-read PacBio Revio technology. Herein, we report on: 1. A domestication and evolution-under-domestication model for tetraploid wheat, derived from integrated genomic and passport data. 2. Identification of novel loci and QTLs from the GDGR for: (i) Resistance to major wheat diseases (yellow rust, leaf rust, stem rust, Septoria tritici blotch, Soil- Borne Cereal Mosaic Virus), (ii) Root system architecture, with a major QTL for root growth angle in chr.6A, (iii) Grain yield components and fertility. Additionally, we highlight recent achievements in understanding the structural variation beyond these QTLs, including the discovery of structural variations strongly associated with key phenotypes. Acknowledgements. PANWHEATGRAIN (PRIN-2020), Grain Pangenomics for Durum Wheat Sustainable Production, AGRITECH, Agritech NationalResearch Center, European Union Next-GenerationEU (PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR) – MISSIONE 4 COMPONENTE 2,INVESTIMENTO 1.4), CEREALMED (PRIMA-2019), INNOVAR, WHEATSECURITY and PRO-GRACE (H2020), Canadian Tetraploid Pan Genomics,National Projects supporting the Svevo Durum Wheat Genome Sequencing Consortium, the Tetraploid Wheat Pangenome Consortium and the developmentof the GDGR.